The immune system controls, at least partially, human papillomavirus (HPV) infection and subsequent tumour development as demonstrated by a higher tumour prevalence in immunodeficient patients. More than ... [more ▼]

The immune system controls, at least partially, human papillomavirus (HPV) infection and subsequent tumour development as demonstrated by a higher tumour prevalence in immunodeficient patients. More than 90% of HPV-infected women will clear the virus within two years. However, it remains unclear which immune cells are implicated in this process and although dendritic cells (DC) and NK cells play a key role in host resistance to virus and tumour, no study has been performed evaluating their crosstalk in this context. Virus-like particles (VLP) formed by the HPV major capsid protein L1 are licensed as vaccine against cervical cancer and we have recently shown that NK cells can directly interact with these HPV-VLP [1]. Here, we investigated the impact of this activation on NK-DC crosstalk. Interestingly, NK cells increase DC maturation induced by HPV-VLP as shown by an up-regulation of HLA-DR and CD86 on DC. Transwell experiments indicated that the expression of HLA-DR is cell-cell contact and soluble factor dependent, whereas only soluble factors seem to be required for CD86 expression. Moreover, in the presence of HPV-VLP and NK cells, DC produce higher amounts of IL12p70, while the production of the immunosuppressive cytokine IL10 remains unchanged. We also demonstrated that DC can up-regulate the expression of NK activation markers (CD69 and HLA-DR) in the presence of HPV-VLP. This up-regulation requires both cell-cell contact and soluble factors. Regarding HLA-DR marker, the increased expression on CD56bright cells is mediated by soluble factors, whereas cell-cell contacts are also important for HLA-DR expression on CD56dim cells. In the presence of DC activated by HPV-VLP, the function of NK cells is also modified since they become more cytotoxic against HPV+ cell line and secrete more IFN-γ. Our results suggest that NK-DC crosstalk could play a role in the immune response induced by HPV-VLP during vaccination protocols against cervical cancer. [less ▲]

Human papillomavirus (HPV) infections account for more than 50% of infection-linked cancers in women worldwide. The immune system controls, at least partially, viral infection and around 90% of HPV ... [more ▼]

Human papillomavirus (HPV) infections account for more than 50% of infection-linked cancers in women worldwide. The immune system controls, at least partially, viral infection and around 90% of HPV-infected women clear the virus within two years. However, it remains unclear which immune cells are implicated in this process and no study has evaluated the direct interaction between HPVs and NK cells, a key player in host resistance to viruses and tumors. We demonstrated an NK cell infiltration in HPV-associated pre-neoplastic cervical lesions. Since HPVs cannot grow in vitro, virus-like particles (VLPs) were used as a model for studying the NK cell response against the virus. Interestingly, NK cells displayed higher cytotoxic activity and cytokine production (TNF-alpha and IFN-gamma) in the presence of HPV-VLPs. Using flow cytometry and microscopy we observed that NK cell stimulation was linked to rapid VLP entry into these cells by macropinocytosis. Using CD16(+) and CD16(-) NK cell lines and a CD16-blocking antibody, we demonstrated that CD16 is necessary for HPV-VLP internalization, as well as for degranulation and cytokine production. Thus, we show for the first time that NK cells interact with HPVs and can participate in the immune response against HPV-induced lesions. [less ▲]

The innate immune response constitutes the first line of host defence that limits viral spread and plays an important role in the activation of adaptive immune response. Viral components are recognized by ... [more ▼]

The innate immune response constitutes the first line of host defence that limits viral spread and plays an important role in the activation of adaptive immune response. Viral components are recognized by specific host pathogen recognition receptors triggering the activation of IRF3. IRF3, along with NF-kappaB, is a key regulator of IFN-beta expression. Until now, the role of IRF3 in the activation of the innate immune response during Varicella-Zoster Virus (VZV) infection has been poorly studied. In this work, we demonstrated for the first time that VZV rapidly induces an atypical phosphorylation of IRF3 that is inhibitory since it prevents subsequent IRF3 homodimerization and induction of target genes. Using a mutant virus unable to express the viral kinase ORF47p, we demonstrated that (i) IRF3 slower-migrating form disappears; (ii) IRF3 is phosphorylated on serine 396 again and recovers the ability to form homodimers; (iii) amounts of IRF3 target genes such as IFN-beta and ISG15 mRNA are greater than in cells infected with the wild-type virus; and (iv) IRF3 physically interacts with ORF47p. These data led us to hypothesize that the viral kinase ORF47p is involved in the atypical phosphorylation of IRF3 during VZV infection, which prevents its homodimerization and subsequent induction of target genes such as IFN-beta and ISG15. [less ▲]

Background The immune system controls, at least partially, human papillomavirus (HPV) infection and subsequent tumor development as demonstrated by a higher tumor prevalence in immunodeficient patients ... [more ▼]

Background The immune system controls, at least partially, human papillomavirus (HPV) infection and subsequent tumor development as demonstrated by a higher tumor prevalence in immunodeficient patients. Around 90% of HPV-infected women will clear the virus within two years. However, it remains unclear which immune cells are implicated in this process and no study has been performed evaluating the direct interaction between HPV and Natural Killer (NK) cells although these cells play a key role in host resistance to virus and tumor. Methods/Results By immunochemistry, we demonstrated an NK cell infiltration in HPV+ squamous pre-neoplasic lesions. Since HPV cannot grow in vitro, virus-like particles (VLP) were used as a model for studying the NK cell response against the virus. Interestingly, NK cells displayed a higher cytotoxic activity (CD107 and chromium release assays) and cytokine production (TNF-α and IFN-γ) in the presence of HPV-VLP. Uptake of HPV-VLP by dendritic cells (DC) has been shown to induce their activation, therefore, we investigated by flow cytometry and microscopy whether the stimulation of NK cell activity is linked to VLP internalization. We observed a faster entry into these cells compared to DC. Furthermore, virus uptake by NK cells is mediated by macropinocytosis, whereas this entry is dependent on clathrin or caveolin endocytosis pathways in DC. Using NK cell lines expressing or not CD16 and blocking antibody, we demonstrated that CD16 is necessary for HPV-VLP internalization, but also for degranulation and cytokine production. Conclusion Thus, we show for the first time that NK cells interact with HPV and could participate in the immune response against HPV-induced tumors. [less ▲]

Cervical cancer, the second most frequent gynaecological malignancy in the world, is caused by infection with high-risk human papillomaviruses (HPV). HPV16 and/or 18 are detected in more than 70% of these ... [more ▼]

Cervical cancer, the second most frequent gynaecological malignancy in the world, is caused by infection with high-risk human papillomaviruses (HPV). HPV16 and/or 18 are detected in more than 70% of these tumours. Prophylactic HPV-L1 virus like particle (VLP) vaccines are highly efficient to protect against HPV16 and HPV18 infection, but not against established infection. In this context, we study the effect of HPV-VLP on natural killer cells (NK) and on the crosstalk between NK and Dendritic Cells (DC). In order to know if HPV-VLP are able to enter in NK cells, we used fluorescent HPV-VLP with flow cytometry and confocal microscopy. HPV-VLP were internalised more rapidly in NK cells than in DC. They were already detected inside NK cells after 10 min of contact at 37°C. We also observed in CD107 assays, that HPV-VLP induce degranulation of NK cytotoxic granules. Previous works have shown that HPV-VLP were able to activate DC. We confirmed these results and observed an increase of CD69 cell surface expression and IFN-γ production by NK cells in the presence of DC activated by VLP. Interestingly, NK cells seemed to further activate DC in the presence of VLP as shown by an up-regulation of HLA-DR and CD86 on DC. Moreover, NK cells in the presence of HPV-VLP induced the production of IL12p70, but not the immunosuppressive cytokine IL10. Our results suggest that NK cells could play a role in the activation of DC induced by HPV-VLP during the vaccination against cervical cancer. Supported by the Belgian FNRS-Télévie [less ▲]